1. Field of Invention
The invention relates to high-efficiency magnetic-type ballasts for fluorescent lamps, particularly of a type using electronic means to assist in the ballasting function.
2. Prior Art and General Background
It is well known that significant improvements in luminous efficacy of fluorescent lighting can be attained by way of using high-frequency electronic ballasts, especially in connection with also using special high-efficacy fluorescent lamps.
Used with ordinary F40/T12 four-foot fluorescent lamps, a good quality high-frequency electronic ballast provides for an overall improvement in luminous efficacy of about 25%. Also using high-efficacy lamps can yield an additional 25% improvement--for an overall efficacy improvement of about 44%.
However, the complexity and relatively high cost of high-frequency electronic ballasts constitute a significant impediment against their widespread use, thereby providing an incentive for finding alternative high-efficiency ballasting means.